Spark plug



C. E. BERSTLE R SPARK PLUG Filed Oct. 12, 1940 Oct. 5, 1943.

y w M v INVENTOR.

(ar/ fimrf/er Arrow Patented Oct. 1943 UNITED STAT PATENTJOFAFICTEV} SPARK PLUG Carl E. Berstler, Reading, Pa. Application'October 12, 1940, Serial No. 360,869

6 Claims. (01. 12 -169) My invention relates to spark plugs, and particularly'to novel means providing more efiective sealing and operation thereof.

In spark plugs of internal combustion engines,

electrical conductors must extend, through openings in the wallsoi the engine heads, into the combustion chambers, and be thoroughly insulated from themetaLand not occupy undue space.

In the more recent greatly increased combustion chamber pressures of automobile and other vehicle'engines, the subject of spark plug leakage, through the insulators along the inner electrodes, has become of added importance, whereby to avoid unexpected failures, causing annoyance and delay in ordinary operation, and more costly results in service of greater importance.

The outer ends of former plugs, in standard practice, have been of simple obvious construction, not especially taking intoconsideration beyond'ordin'ary expediency the masses, shapes'and relatio-ns'of the conducting and non-conducting elements,not being guarded sufliciently against gas leakage, deterioration and injury, andnot being especially adapted for 'form and setting, or for temperature and electric control.

Also, the factor of fouling of the plugs at the firing ends, which has always been a difiicult problem, has become increasingly so from the greater danger of the above-mentioned leakage in modern practice. i

The inner ends 'of spark plugs have'b'een the subject of probably hundreds of experiments, and very minor physical changes of the shapes, volumes or masses, and relations of metal, insulating material and free space, sometimes cause variations of operation greatly out of proportion to the apparent extent of such changes.

Further, plugs of onemake,'size and type may be required to operate in any of various classes or work, represented by pleasure cars, light and heavy trucks, tractors, motor boats, and the'like, and each of these subject to varying degrees of light or heavy, and continuous or intermittent operation, under all of weather, temperature, load and otherc'onditions. i

Fouling occurs from various reasons, such as poor mixtures of gas and air, oil in the combustion chambers, cold starting, incomplete combustion, and other efiecta so that, in designing a plug, all of thesefactors must be considereds" Plugs' of standardand well. known makes have tubularinner-endshell portions through, or into, which extend'the inner electrodes, and the inner end portions or tips of the insulators, the come bined masses ofthe insulator and electrode materials occupying most of the spacelin the innerend shell portions. I 1 I These shell portions, the inner ends of which are open, form dead-air spaces or pockets about. the insulators, which, because of the above-mentio-nedspace'occupancy of the insulator and electrode masses'in' the inner end of the shell; lack of fluid circulation through the shell walls, or for other reason, apparently do not receive the fire or;

heat of combustion to sufiicient extent to maintain the insulators clean, and do not contain good mixtures for fast burning.

It is among the objectsof my invention to overcome all of the above-mentioned objections, and to providea spark plug that shall not only be more effective, but, that shall remain efiective over a greater period of time. r

Another object .of the invention is to so seal a spark plug asto prevent leakage through the insulator along the inner electrode, and to effect such sealing whereby to render it lasting, and free from undue complication and expense.

Another object of the invention is to improve the form, protection, durability and operation of a spark plug at its outer enol.

Another object of the invention is to provide a novel spark plug inner-endstructure whereby to improve theoperation of an engine, to prevent fouling of the plug, and to render the outer end more effective. 7

Another object of the invention is to improve both ends of aspark plug, each in relation to the other, as in sealing the plug at its outer end to prevent fouling at the inner end, and to improve the circulation. and combustion of gas at the inner end whereby to render the outer end more durable, and the plug andthe engine more efiicient, without changing the engine parts.

Another object of the invention is to provide a spark plug with a seal having a path, along which gas tends to escape, that shall be tortuous, locally blocked by pressure concentrating elements, and augmented by hardened fluid sealing material in a manner eiiectively preventing such escape.

Anotherobject of the invention is to provide the by means ofeither or both the feature of en'- larging the free space between an inner end length of the shell and the insulator, and the feature of providing passageway means through and along the exterior of the side wall .of .the inner shell length.

Another object of the invention is to :provide' a spark-plug seal, and its method of assembly, whereby to facilitate the effectuating of strong mechani cal ipressure between the seal :parts, without undue friction, or the. requirement for the application of undue fame, and to prepare certain of the parts subject :to su h pressure in avoid disruption thereof.

- A further object dfzthe in enticnis to provide a spark slug that shall be simple and .durabm in construction, economic l to manufacture, and efiectiue in its operation.

with such objects. view, :as Well as other advantages which may be :incidcntto a utilization of the improvements, the fin-Mention com prises the elements and combinations thereof hereinazfiter set forth thespecification, draw-- ing and claims; with the understanding that the sever-all necessary elements constituting the same may be varied in proportion, arrangement and texturegwithout departing from the :nature'and scope Offthe invention.

in .order to make :the invention more clearly understood, means are shown :in the accompanying drawing for carrying the same into practical effect, without iimitingthe improvements, in the useful. applications thereof, to the particular constructions, assemblies and operations which, for

the purpose .ofxexplanationyare made the sub ject of illustration.

In the drawing:

Figure 1 is an enlarged view, partially in side elevation, and partially in vertical central-plane section, .of a .sparkplug constructed in accordance with the invention;

Fig. 2 is a bottom plan view of the structure of Fig, '1;

Fig. 3 is an elevational view, taken at right angles to Fig. Lie-om the left thereof, of the lowerportion of thep'lug; I

Fig. 4 is .a view on a scale reduced from that of 1,.partially in side elevation and par.- tially in section, of an insulator, an inner electrade, and ontereen-d seai and terminal parts of a spark plug constituting a modification of the i n: and r V Flgfi' m inc usive, are views. similar to the oo portion of Fig.1.. of the invention therens through the cap structure.

man efiectiye form of the invention, hardened fluid sealing material desirably augments the gasket seal on the cap, insulator and gasket parts in or about the latter. Either the cap or the outer insulator end may have the form of a cup surrounding the gasket means, or fitted over a projection on the other, and pressing the asket means.

In each of several effective forms of the invention, the porcelain has, or is provided with, an outer-end gasket seat, whereby thelatter surrounds, cr is surrounded by, a portion of the insulator material.

:Correspondingly, in any of the latter forms, the fluid-impervious cap may telescope the insulator means radially inwardly or outwardly thereof, or .both, whereby to form a tortuous path against the escape of gas.

'The cap, although desirably of one metal piece having -a distributor cord terminal connector portion, more effectively of the snap-fastener, or quick-detachable type, is in any event, adapted to have the terminal cooperate with the electrode through the imperforate, or rfiuideimperv-ious, portions thereof. a

To avoid irregularities or inequalities of pres:

sure, as occurs between cooperating broad-area gasket pressure faces, -.caused by discrepancies in the "uniformity of the faces, torednce friction limits of the structure surrounded by a portion.

of the insulator or the can.

In an effective form, gasket means is placed between the insulator and ,a terminal element rotatively or screw *threadably mounted on an electrode secured to the insulator. One portion of the insulator and terminal cooperates with the gasket :means to prevent turning of the latter, and another portion cooperates with the gasket means for reduced friction contact therewith.

Such outer-end structure increases the emc'iency, and reduces fouling, of the inner end of the plug irrespective "of the particular construction of the latter, but more effectively in combination with the form or forms of the'present invention, whereby the inner-end length of the shell either or both has a perforate side wall cooperating with passageway means along the outer side of such wall to the inner end of the shell for communication with the combustion chamber of an engine, and cooperates with the insulator and inner electrode means to provide more free space along :the inside of such inneraend shell length.

The latter feature alone, or with the outer-end ring structure hereof, eliminates the dead-air space heretofore in the inner end of the shell, provides circulation of the gas and fire of combustion .all about the inwardly exposed insulator surface in the inner end of the shell, thereby maintaining such surface clean, or rendering it self cleaning, and adds its volume or circumscribed space to that of the combustion chamber proper, with the result of better circulation and faster burning in the thus enlarged combustion chamber as a whole, greater power, better pick up, and easier starting of the engine, and longer maintenance of these qualities.

Referring to the drawing, as better seen in Fig. 1, a spark plug constructed in accordance with one form of the invention comprises, ingeneraLTdieIectric or insulating means D, inner electrode means E, outer-end terminal means a shell Shaving aninner-end combustion chamber portion C, and ground electrode means Gon the sh'ellportionC; ,7

"Theinsulator means D, although it may be constructed Qfvarious numbers and kinds of materials, and parts, is shown, in this instance, of one homogeneously integral piece, known as a porcelain, having an .outer-end length I! pro truding from the shells, a body l8, and a :lowerend=leng'th:or:tip .elementl9." The body It is of greaterfdiameter than the1outer and inner-end lengths, Hand l9,: respectively, to provide upper and lower: shoulders onthe body constituting seats for sealing gaskets.22:and"23, respectively,

disposed betweenthe insulator D and the shell S. The insulator has an-opening extending entirely, therethrough around the central longitudinal axis of the plug, this opening having a smooth cylindrical surface-about thejlower length of the of larger diameter for c'ooperation'with a screw threaded portion 24 of the electrode E..

The upper-end length I! of the insulator means Dhas, in the form of Fig.1 1, a fiat-plane transverse end surface, or: shoulder at right angles to the electrode means, in whichshoulder is provided an annular groove or channelfor the reception of'agasketll, '1

. :The electrode means ,E further comprises a screwthreaded top-end: length 28, an arcing lower-endlength '29,- and'a; disk-like portion 30 forming a part of the electrode, or sealed thereto,

' and extending laterally therefrom overthe outerend-"surface or shoulder having the above-mentioned groove for thegasketll. '1

In such instance therefore, the gasket both surrounds, and; is surrounded by, portions of the insulator 13 forming the groove for the gasket, and is radially spaced'inwardlyfrom the outer limits of the insulator, ,and outwardly from the outer limits of the portion ,30.

v The outer-end terminal'means T, shown in this instance as'of onehomogeneously integral piece of metal, such as brass, which may be lacquered, or, chromium or nickel plated, has a cap-like por:

tom flange 34 surrounding the gasket 27, and the portion 30 of the electrode means EL The cap or dome portion 32,; -in this instance, is thus of inverted substantially cup-shape, having a counterterminal. T, ,orxall partslicemented together and subsequentlybaked v When the terminalT and the insulator D are advanced toward each other, by action of the terminal T on the screw threaded topendlength thereby very greatly increasing the resistance to the leakage of fluid through the plug'along the i electrodeunder the violent urge of the compressed prior practice.

I electrode'E, and a screw threaded-upper length and exploded gases from the combustion chamber, over the resistance offered by the plugs ,of

Although shown as in agroove in the insulator,- against afiat face of the terminaLT, this relation may be reversed, whereby the gasket engages a large surface in -;the groove to hold the gasket against turning, and the flat face, which initially has only line contact, and never very great surface contact, with the gasket, thus reduces the friction of the contact compared to that between. broad areasurfaces, as above mentioned. The terminal means T, having a metallic ex-v posed surface of substantiallycontinuous laterally outward and longitudinally inward slope, or

convex curvature, from the outer-end portion 33 thereon to the line of meeting of the flange 34 with the insulator D, and constituting substan-' tially an uninterrupted extension of the insulator length ILhas remarkably efiective form or setting. Having substantial metallic body, and surface area, the means Talso contributes to cooling theplug, and more widely and uniformly spreads the electric field than do the usualsmaller metal,

\ top parts of ordinar lugs.

The shell s has a top flange 31'pre'ssed inwardly and downwardly over the gasket 22, a tapered lowerinner body seat against which the gasket 23 and the insulator body 18 are forced by the flange 37,;and a bottom shoulder 33 for seating on agasket on an engine head'into an opening of which the inner-end shell portion C extends.

The portion C, see Figs. 1, 2 and 3, has, inthis instance, aperture, means through its longitudinal side wall, in the form of three; holes 42 near the shoulder 38 equally spacedabout the plug. Grooves 43, which conceivably, in certain instances, might be provided in the engine head, are however believed generally more effectively provided in the shell, as shown, each extending from one of the holes-42, and cutting through, or traversing, screw threads 44 on the portion 0 to Q ,the inner end of the latter, forcommunication.

sunk lower face surrounded by thefiange 34 for pressure against the'gasket 21, andwhich may also be provided with a complemental groove for seating over, andabout and Within, the gasket similar to the manner in which the insulator groove seats under, about and within the gasket. In assembling the parts, a hardening fluid sealing material, such as cement, is placed all along the length of the electrode E in the insulator D, over and under the gasket 21 and the portion 39,

between the gasket and the flange 34, under the latter, and betweenfthe gasket'and the portion 30. ,Such parts may be baked to set the cement and anchor the electrode before mounting the with the combustion chamber of the engine.

By this construction, in which the number,-

form and relation of the holes and grooves may be varied, the exposed surface of the insulator tip 33, is subject to the fire of combustion, whereby to maintain the plug clean at this tip, or to render it self cleaning, if fouled before use with the invention. i

As shown, the tip I5 extends only a short distance into the shell portion C, thereby providing free space of substantial volume relative to the mass of the insulator and electrode means along the portion 0 for better circulation of gas and the tire of combustion. This tip may be of other shape and diameter, and extend a greater or less distance toward the ground electrode G theaabove-ment-ioned circulation, and it is con- I templated'that the additional freeispacethereby provided may be utilized alonej'orin'combination with the holes 42 and'the grooveslidor equivalentmeans'; f The free space withinthe shellportion C, around .the insulator tip [9, which heretofore acted as a dead air space, and in'many cases readily became literally choked with carbon, be-' comes, by the invention, entirely free from such fouling.

o'In'the form of Fig. 1, the compression of the gasketfl reacts between the terminal '1 and the threaded portion 24 of the inner electrode E,

' constituting-an integral part of, the electrode M,

which enlargement has a tapered or beveled top seat engaging a corresponding seat at the top of an enlarged lower portion'52 of the opening in the insulator through which the electrode e'X- tendsQThiS insulator and electrode'arefree from thes'crew'threads at the upper part of the in.-

sulator of Fig. 1, as well as of the disl: '-like'por-.

tion Hover the top of the insulator.

Asshown in the form of Fig. 5, a terminal Ta.

tele'scope s radially and longitudinally inwardly of an insulator Da,'through a series of steps forming seats for gaskets 53. insteadof the single gasket 2T, the terminal being free from the bottom flange 34, although such flange maybe provided,

and cooperating with al'onger upper screw thread portion on an inner electrode Ea.

In the form of Fig. 6,"'a terminal Tb has a v separable snap fastener portion 51, as may any of'the forms, instead of the integral portion 33 of Fig. 1.- The terminal Tb also has depending lower portions 58 telescoping longitudinally inwardly, and radially and outwardly, of portions of an insulator Db, in which gaskets 59, corresponding to the gaskets 53 of Fig. 5, are similarly compressed, and form a different tortuous path against gas leakage. I

An inner electrode Eb has a shorter upper screw thread portion corresponding to the portion 28 of Fig. 'l, and is disposed substantially entirely within the insulator Db.

In the form of Fig. '7, the structure is similar to the form of Fig. l, in having. like insulator means D; electrode means E, screw threaded portions 25 and 28, a portion 36,, and a gasket ZLbut a terminal To is additionally provided with a flange .64, rounded for electrostatic, and other purposes, and telescopingthe upper end of the insulator D, whereby to. surround the gasket 2'1, and to provide additional sealing.

InFi'g. 8, an insulator Dd has a sloping top end seat for a similarly sloping gasketfi'l, and an inner electrode E having the screw thread portions' 24 and 28, the disk-like portion. I A terminal Td has a sloping seat for engagement with the gasket 51, and a depending flange 68, similar to'the flange 3B, of Fig. 1, disposed over a flat annular top surface portion .on the insulator around the. sloping gasket seat thereof.

In Fig. 9, the'structure is similar to that of 8, including an electrode E having the screw thread portions 24 and 28, andthe disk portion; 30.. Seats on an insulator Defand a terminal Te, although sloping as in the device of 8,-

are rounded to compress a gasket 69 therebetween; In this form,v the. top end of the insulator De is similar to the top ends of insulators heretofore employed, with theexception' of a shoulder E2, removalof which would leave the device still operative, thus illustrating how the invention may be applied to such former insulators; In the latter case, however, the lower end of. the terminal 'I'ccould be modified to give better symmetry. I e 1 As shown in Fig. 10, the structure islsimilar to that of Fig. 6, with the outer portion 58 of the latter removed, and an'insulator *Df not-having a seat for a gasket .underth'e' flange.- An electrode Ej'likewise does not project from the top of the insulator, and a'terminal T compresses gaskets E3 againstthe insulator, the inner gasket being. disposed over a disk-like portion similar to the portion 36! ofFig, 1. Further, surfaces Id on the terminal T such as the'side'surfaces of a nut; or flat areas on a-cylinden'may be providediin any of the forms, or holes or slotsyor othermeans substitutedtherefor to cooperate with a wrench or the like in mounting the ter minal in position.

In Fig. 11; a terminal T9 is similar to the terplied as set forth abov'e. i

The number of forms shown is not an attempt to set forth all, but only within reasonable illus-' tration, of elements which maybe produced within the purview of the actual invention.

I claim as my invention:

'1. A spark plug comprising electrode means, insulator means surrounding said electrode means, and a shell surrounding the insulator means including a tube-like inner end length having fluid passageway means laterally therethrough and means providing for the passage of fluid between said passageway means and the inner end of said tube along a substantial length of the latter closed to the interior thereof.

2. A spark plug comprising electrode means, insulator means surrounding said electrode means, and a shell surrounding the insulator means including a tube-like inner end length having fluid passageway means" laterally therethrough and groove means of substantially channel section extending along the'exterior of the tube from said passageway means to the inner end of the tube.

3. A spark plug comprising electrode means, insulator means surrounding said electrode means, and a shell surrounding the insulator means including a portionsealed relative to the insulator means and a tubular-wall inner end length having fluid passageway means laterally therethrough closely adjacent to'said sealed portion and means providing forthe passage of fluid along a length of said tubular wall closed to the interior of the, tube between said passageway means and the inner end of the tube.

.4. A spark plug comprising electrode means.

insulator means "surrounding said electrode means, and a shell surrounding the insulator means including a portion sealed relative to the insulator means and an exteriorly screw threaded tube-like inner end length having aperture means laterally therethrough closely adjacent to said sealed portion and means intersecting the screw threads providing for the passage of fluid along a length of said tube closed to the interior of the tube between said aperture means and the inner end of the tube.

5. A spark plug comprising electrode means, insulator means surrounding said electrode means, and a shell surrounding the insulator means including a portion sealed relative to the insulator means and a tubular-wall inner-end length having fluid passageway means laterally therethrough closely adjacent to said sealed portion and groove means of substantially channel CARL E. BERSTLER. 

